57P05

At a glance

57P05 terminates a session after idle_session_timeout expires while the backend is truly idle between commands. The fixed code starts this timer only in the no-transaction branch; idle-in-transaction has a separate condition and timer.

Meaning

The fixed primary is terminating connection due to idle-session timeout at FATAL. In PostgresMain, the idle-session timer is enabled after the backend reports STATE_IDLE and only in the branch where IsTransactionOrTransactionBlock() is false. The timer is disabled as soon as a command is read. This makes 57P05 a session-lifecycle termination, distinct from statement timeout 57014, lock timeout 55P03, idle-in-transaction timeout 25P03, and transaction timeout 25P04.

Messages

• Primary: terminating connection due to idle-session timeout.
• Severity: FATAL; the timer interrupt terminates the connection rather than returning a recoverable statement ERROR.
• Boundary: a truly idle session between commands uses 57P05; a session idle inside an open transaction uses the separate idle-in-transaction timer/condition.

Diagnosis

Capture the primary, backend PID, idle_session_timeout value and source, last command, pg_stat_activity state, transaction status, and server log. Verify whether the session was idle or idle in transaction when the timer started. Elapsed client request time alone cannot distinguish this from statement or lock timeout, and the SQLSTATE should be interpreted with the connection's last ReadyForQuery state.

Response

Close or recreate the expired connection and make long-lived work explicit rather than holding an unused session. Adjust idle_session_timeout only when policy permits and the workload needs it. Because FATAL closes the connection, there is no useful ROLLBACK command to send on that session; after reconnecting, verify durable effects before replaying a non-idempotent command. If the workload was idle in a transaction, diagnose 25P03/25P04 and transaction ownership separately.

Versions

The locked catalogue records this condition from 14.0; that boundary does not prove the exact implementation-introduction version. Fixed source coverage is PostgreSQL 18.6.

Related

57P01, 25P03, 25P04, 57014, 55P03

Sources

src/backend/tcop/postgres.c#L3504-3513

src/backend/tcop/postgres.c#L4585-4650

src/backend/tcop/postgres.c#L4704-4721

The structured evidence record records the message and idle-state boundary.

Source evidence

Evidence belongs to the frozen source and runtime versions listed here. It is not a runtime verification of the selected manual version.

• src/backend/utils/errcodes.txt · REL_18_6 ·
  724edf9bde9d356724ad384a2e196edc3c9f80f7
• src/backend/tcop/postgres.c · REL_18_6 ·
  724edf9bde9d356724ad384a2e196edc3c9f80f7
• src/backend/tcop/postgres.c · REL_18_6 ·
  724edf9bde9d356724ad384a2e196edc3c9f80f7
• src/backend/tcop/postgres.c · REL_18_6 ·
  724edf9bde9d356724ad384a2e196edc3c9f80f7

Message templates

terminating connection due to idle-session timeout

Reproduction & repair cases

No reproduction case is attached to this condition.

Recorded runtime evidence

No runtime observation is attached to this entry.